<?

/**
@author Nguyen Quoc Bao <quocbao.coder@gmail.com>
@version 1.3
@desc A simple object for processing download operation , support section downloading
Please send me an email if you find some bug or it doesn't work with download manager.
I've tested it with
   - Reget
   - FDM
   - FlashGet
   - GetRight
   - DAP

@copyright It's free as long as you keep this header .
@example

1: File Download
   $object = new downloader;
   $object->set_byfile($filename); //Download from a file
   $object->use_resume = true; //Enable Resume Mode
   $object->download(); //Download File

2: Data Download
$object = new downloader;
   $object->set_bydata($data); //Download from php data
   $object->use_resume = true; //Enable Resume Mode
   $object->set_filename($filename); //Set download name
   $object->set_mime($mime); //File MIME (Default: application/otect-stream)
   $object->download(); //Download File

   3: Manual Download
   $object = new downloader;
   $object->set_filename($filename);
$object->download_ex($size);
//output your data here , remember to use $this->seek_start and $this->seek_end value :)

**/

class httpdownload {

var $data = null;
var $data_len = 0;
var $data_mod = 0;
var $data_type = 0;
var $data_section = 0; //section download
/**
* @var ObjectHandler
**/
var $handler = array('auth' => null);
var $use_resume = true;
var $use_autoexit = false;
var $use_auth = false;
var $filename = null;
var $mime = null;
var $bufsize = 2048;
var $seek_start = 0;
var $seek_end = -1;

/**
* Total bandwidth has been used for this download
* @var int
*/
var $bandwidth = 0;
/**
* Speed limit
* @var float
*/
var $speed = 0;

/*-------------------
| Download Function |
-------------------*/
/**
* Check authentication and get seek position
* @return bool
**/
function initialize() {
   global $HTTP_SERVER_VARS;

   if ($this->use_auth) //use authentication
   {
    if (!$this->_auth()) //no authentication
    {
     header('WWW-Authenticate: Basic realm="Please enter your username and password"');
       header('HTTP/1.0 401 Unauthorized');
       header('status: 401 Unauthorized');
       if ($this->use_autoexit) exit();
     return false;
    }
   }
   if ($this->mime == null) $this->mime = "application/octet-stream"; //default mime

   if (isset($_SERVER['HTTP_RANGE']) || isset($HTTP_SERVER_VARS['HTTP_RANGE']))
   {
   
    if (isset($HTTP_SERVER_VARS['HTTP_RANGE'])) $seek_range = substr($HTTP_SERVER_VARS['HTTP_RANGE'] , strlen('bytes='));
    else $seek_range = substr($_SERVER['HTTP_RANGE'] , strlen('bytes='));
   
    $range = explode('-',$seek_range);
   
    if ($range[0] > 0)
    {
     $this->seek_start = intval($range[0]);
    }
   
    if ($range[1] > 0) $this->seek_end = intval($range[1]);
    else $this->seek_end = -1;
   
    if (!$this->use_resume)
    {
     $this->seek_start = 0;
    
     //header("HTTP/1.0 404 Bad Request");
     //header("Status: 400 Bad Request");
    
     //exit;
    
     //return false;
    }
    else
    {
     $this->data_section = 1;
    }
   
   }
   else
   {
    $this->seek_start = 0;
    $this->seek_end = -1;
   }

   return true;
}
/**
* Send download information header
**/
function header($size,$seek_start=null,$seek_end=null) {
   header('Content-type: ' . $this->mime);
   header('Content-Disposition: attachment; filename="' . $this->filename . '"');
   header('Last-Modified: ' . date('D, d M Y H:i:s /G/M/T' , $this->data_mod));

   if ($this->data_section && $this->use_resume)
   {
    header("HTTP/1.0 206 Partial Content");
    header("Status: 206 Partial Content");
    header('Accept-Ranges: bytes');
    header("Content-Range: bytes $seek_start-$seek_end/$size");
    header("Content-Length: " . ($seek_end - $seek_start + 1));
   }
   else
   {
    header("Content-Length: $size");
   }
}

function download_ex($size)
{
   if (!$this->initialize()) return false;
   ignore_user_abort(true);
   //Use seek end here
   if ($this->seek_start > ($size - 1)) $this->seek_start = 0;
   if ($this->seek_end <= 0) $this->seek_end = $size - 1;
   $this->header($size,$seek,$this->seek_end);
   $this->data_mod = time();
   return true;
}

/**
* Start download
* @return bool
**/
function download() {
   if (!$this->initialize()) return false;

   $seek = $this->seek_start;
   $speed = $this->speed;
   $bufsize = $this->bufsize;
   $packet = 1;

   //do some clean up
   @ob_end_clean();
   $old_status = ignore_user_abort(true);
   @set_time_limit(0);
   $this->bandwidth = 0;

   $size = $this->data_len;

   if ($this->data_type == 0) //download from a file
   {
   
    $size = filesize($this->data);
    if ($seek > ($size - 1)) $seek = 0;
    if ($this->filename == null) $this->filename = basename($this->data);
   
    $res = fopen($this->data,'rb');
    if ($seek) fseek($res , $seek);
    if ($this->seek_end < $seek) $this->seek_end = $size - 1;
   
    $this->header($size,$seek,$this->seek_end); //always use the last seek
    $size = $this->seek_end - $seek + 1;
   
    while (!(connection_aborted() || connection_status() == 1) && $size > 0)
    {
     if ($size < $bufsize)
     {
      echo fread($res , $size);
      $this->bandwidth += $size;
     }
     else
     {
      echo fread($res , $bufsize);
      $this->bandwidth += $bufsize;
     }
    
     $size -= $bufsize;
     flush();
    
     if ($speed > 0 && ($this->bandwidth > $speed*$packet*1024))
     {
      sleep(1);
      $packet++;
     }
    }
    fclose($res);
   
   }

   elseif ($this->data_type == 1) //download from a string
   {
    if ($seek > ($size - 1)) $seek = 0;
    if ($this->seek_end < $seek) $this->seek_end = $this->data_len - 1;
    $this->data = substr($this->data , $seek , $this->seek_end - $seek + 1);
    if ($this->filename == null) $this->filename = time();
    $size = strlen($this->data);
    $this->header($this->data_len,$seek,$this->seek_end);
    while (!connection_aborted() && $size > 0) {
     if ($size < $bufsize)
     {
      $this->bandwidth += $size;
     }
     else
     {
      $this->bandwidth += $bufsize;
     }
    
     echo substr($this->data , 0 , $bufsize);
     $this->data = substr($this->data , $bufsize);
    
     $size -= $bufsize;
     flush();
    
     if ($speed > 0 && ($this->bandwidth > $speed*$packet*1024))
     {
      sleep(1);
      $packet++;
     }
    }
   } else if ($this->data_type == 2) {
    //just send a redirect header
    header('location: ' . $this->data);
   }

   if ($this->use_autoexit) exit();

   //restore old status
   ignore_user_abort($old_status);
   set_time_limit(ini_get("max_execution_time"));

   return true;
}

function set_byfile($dir) {
   if (is_readable($dir) && is_file($dir)) {
    $this->data_len = 0;
    $this->data = $dir;
    $this->data_type = 0;
    $this->data_mod = filemtime($dir);
    return true;
   } else return false;
}

function set_bydata($data) {
   if ($data == '') return false;
   $this->data = $data;
   $this->data_len = strlen($data);
   $this->data_type = 1;
   $this->data_mod = time();
   return true;
}

function set_byurl($data) {
   $this->data = $data;
   $this->data_len = 0;
   $this->data_type = 2;
   return true;
}

function set_lastmodtime($time) {
   $time = intval($time);
   if ($time <= 0) $time = time();
   $this->data_mod = $time;
}

/**
* Check authentication
* @return bool
**/
function _auth() {
   if (!isset($_SERVER['PHP_AUTH_USER'])) return false;
   if (isset($this->handler['auth']) && function_exists($this->handler['auth']))
   {
    return $this->handler['auth']('auth' , $_SERVER['PHP_AUTH_USER'],$_SERVER['PHP_AUTH_PW']);
   }
   else return true; //you must use a handler
}

}

?>